Invoice or bill?

The same sheet, two directions

You do the work and ask for money: that is an invoice, and to you it is a receivable. Your client receives that identical sheet and files it as a bill — a payable, money they owe. Same parties, same lines, same total; the only thing that changed is who is reading it.

Which is why Perly has one editor for both. Choosing the direction swaps the parties and the numbering series, and everything else — the lines, the arithmetic, the currency, the payment block — is the same document.

Why record what you owe as well

• You find out what a month actually costs. Subcontractors, software, the accountant, the one licence nobody remembers buying.
• Nothing goes unpaid by accident. A bill with a due date behaves exactly like an invoice: it goes overdue on its own, and says so.
• Your books balance at the end of the quarter without a reconstruction from bank statements and a folder of PDFs.

Separate series for each

Your invoices are yours to number — one ascending series, your prefix. A bill's number is the supplier's: you record it as it arrives, because that is the number they will refer to when they chase it. Keeping the two series apart is what stops your own numbering from having gaps in it.

What about a receipt, a quote, a statement?

• A quote is a price before the work, and creates no obligation.
• An invoice is the request for payment after it, and does.
• A receipt is the acknowledgement that it was paid.
• A statement is a list of invoices over a period, not a request for any one of them. Sending a statement when you meant an invoice is a common and expensive mix-up.

Perly makes the middle two — the invoice, and the same document recorded as a bill — and marks a document paid with the date it happened, which is the part of a receipt that matters.